Dichloro-oxypurin and process of making same.



' Nrrn STATES ATENT Prion.

LORENZ AOH AND FRITZ AOH, OF MANNHEIM, GERMANY, ASSIGNORS TO 0. F. BOEHRINGER & SOEHNE, OF WALDHOF, GERMANY.

DICHLORO-OXYPURIN AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 654,122, dated July 24, 1900.

Application filed June 14, 1897. Serial No, 640,762. (Specimens) To all whom it may concern:

Be it known that we, LORENZ ACH and FRITZ AOH, citizens of the Empire of Germany, residing at Mannheim, Germany, have invented certain new and useful Improvements in the Art of Preparing Purins; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to the art of preparing compounds belonging to the class known as purins, and more particularly to halogen-oxy-purins such as the body which we are the first to have produced and which we term dichloro-oxy-purin.

For an explanation of the term purin employed in this specification reference is made to Beriohte der Deatschen O'he'mischert Gesellschajt, Vol. 30, p. 549 and to Abstracts ofthe British Chemical Society,Vol.46, (1884,) p. 996 et. seq.

Purin derivatives, such as chloro-methylpurins or chlorated methyl-purins, of which dichloro-oxy-dimethyl-purin having the structural formula:

NzOCl 01.0 ON.OH3

(see Berichte der Deutsohcn Ohemischen Gesellschaft, Vol. 17, p. 1782, and Abstracts of the British Chemical Society, Vol. 44, p. 996,) may be given as an example, have hitherto been obtained from various alkyl derivatives of uric acid and xanthin (among them theobromin and caffein) by the action of phosphorus-pentachlorid in connection with phosphorus-oXy-chlorid, which acts as a solvent. (Berichte der Deatschen Ohemischeri Gesellschaft, Vol. 17, p. 330, and Vol. 28, p. 2480.) Hitherto, however, all attempts to remove oxygen from uric acid, and thus to attain the production of purin derivatives free from methyl, have been unsuccessful. (Berichte der Deatschen Ohcmischen Gesellschaft, Vol. 17, p. 329.)

All attempts to convert uric acid properthat is to say, uric acid in which none of the four nitrogen atoms have been combined with an alkyl radicalinto a ohloro-purin have failed. I have found that this failure must be attributed to the fact that in allcases such conversion has been attempted by causing phosphorus-oxy-chlorid to act upon such uric acid proper, together with phosphorus-pentachlorid. This method, while it leads to good results with alkylized uric acids, is attended by a complete destruction of uric acid proper. It is my discovery that the production of alkyl-free-chlor o-purins may be attained if we employ only phosphorus-oxy-chlorid without any addition of phosphorus-penta-chlorid. In all the former processes and experiments with methylized or alkylized uric acids the phosphorus-oxy-chlorid performed merely the part of a solvent and diluting medium, while the function of withdrawing the oxygen and at the same time chlorinating the uric acid was performed solely by the phosphorus-pentachlorid. All the prior experimenters failed to recognize the fact that the phosphorus-oxychlorid alone could be employed to perform this latter function of chlorinating the uric acid. The gist of our invention, therefore, is based mainly upon our discovery that phosphorus-oxy-chlorid alone may be employed for chlorinating uric acids.

It is the object of our invention to attain this result; and the said invention consists in the method which we have discovered foraccomplishing this purpose and in the compound which is produced in carrying out the said method.

Our invention consists, primarily, in the action of a phosphorusoxy-halogen compound, such as phosphorus-oxy-chlorid, upon uric acid and also the salts of uric acid.

The invention, moreover, consists in such details of the method thus broadly characterized and other features, as will be hereinafter set forth, and pointed out in the claims hereunto appended.

We will now proceed to describe the same as applied to the production of the new compound, dichloro-oxypurin, having the composition indicated by the formula C H N 001 The salts hitherto employed in this IOO process are the acid potassium, sodium, ainmonium, magnesium, calcium, and barium salts of uric acid.

In illustration of our invention we will now proceed to describe what we consider the best method of carrying the same into effect. We will first show how the same may be obtained by the action of phosphorus oxychlorid upon a dry salt of uric acid and then describe its production by causing the phosphorus-oxy-chlorid to act upon the free uric acid.

Example 1.-The following example will serve to fully illustrate our invention when employing a urate: One kilogram of acid urate of potassium in a dry state is well.

mixed with one and two-tenths kilograms of phosphorus-oxy-chlorid, then heated to 160?- centigrade and maintained at this temperature for four hours in a closed vessel. excess of oxy-chlorid is distilled off, and the residue is then washed with water. The resulting product is not quite pure, since a small amount of unchanged uric acid remains therein. All impurities are, however, readily removed by nitric acid. The dichlor-oxypurin may also be obtained in a pure condition by separating the same in the form of an ammonium-salt from aqueous or alcoholic solutions.

. Example 2.When employing free uric acid, the following is the preferable method of proceeding: One part, by weight, of uric acid, together with five parts, by weight, of phosphorus-oxy-chlorid, is heated in a digest'er to from 170 to 175 centigrade and maintained at this temperature for from twenty-four to thirty hours, the mass being constantly agitated. After the lapse of this time the uric acid is completely dissolved. The resulting liquor, which has a brownish color, is evaporated to complete dryness in vacuo to remove the phosphorus-oxy-chlorid. The amorphous residue is dissolved in alcohol, (preferably pure.) The dichlor-oxypurin separates out of the clear alcoholic solution in the form of coarse yellow crystalline grains after boiling for a half-hour and concentrating. To completely purify the same, it is warmed or heated for a short time with nitric acid of the specific gravity 1.41. It is thus obtained colorless. The yield is about from forty-five to fifty per cent. of the by oxidizing agents-such as, for example,-

strong nitric acid. Moreover, it forms a permanent silver salt with an ammoniacal silver solution. It is soluble with extreme difficulty in water. From alcohol, by which it is taken up only with difficulty, it is obtained in very small needles, which are decomposed at a temperature of over 300 centigrade. By methylation the dichlor-oxy- The purin is very readily converted into dichloroxy-dimethyl-purin, which has already been prepared by Emil Fischer, and which has the following composition:

N=CCl N-o-NoH,

(see Bem'chte der Deutschen Chemischen Gesellschaft,Vol. 17, pp. 328 and 1787.) From this it follows that the present product, which is free from alkylnamely, the dichloro-oxypurin-must have the composition indicated in the following formula:

From the location of the chlorine and oxygen atoms we designate the sameas (2-6) dichlor (8) oxy-purin.

It will be seen from the above that the process may be varied in many respects without departing from our invention. Instead of the potassium urate other salts of uric acid may, for example, be employed, the essential point of the invention, broadly considered, being the treatment of a uric-acid radical comprised either in uric acid proper or in a urate, with an oXy-halogen compound of phosphorus, differin g in this respect materially from the processes set forth in United States Patents Nos. 631,758 and 631,759 of August 22, 1899, to Fritz Ach, under which alkyl uric acids are so treated.

What we claim, and desire to secure by Letters Patent, is- 1 1. The process which consists in acting upon a compound containing the acid radical of uric acid proper with an oxy-halogen compound of phosphorus.

2. The process which consists in acting upon a urate with an oxy-halogen compound of phosphorus.

3. The process which consists in acting upon a urate with oxy-chlorid of phosphorus.

4:. The process which consists in acting upon an acid urate with oxy-chlorid of phosphorus.

5. The process which consists in heating acid urate with phosphorus-oxy-chlorid in the proportions and in the manner substantially as specified.

6. The process which consists in heating acid urate of potassium with phosphorus-oxychlorid in the proportions and in the manner substantially as specified, then distilling of: the excess of oxy-chlorid and washing the residue.

IIO

7. The process which consists in heating which are decomposed ata temperature over dry acid urate of potassium with phosphorus- 300, centigrade, and which forms a permaoxy-chloridin the proportions and in the mannent silver salt remaining unchanged in an I 5 ner substantially as specified, then distilling ammoniacal solution.

5 off the excess of oxy-chlorid and washing the In testimony whereof we affix our signaresidue and purifying the same. tures in presence of two witnesses.

8. As a new compound dichlor-oxy-purin having the formula hereinbefore given, which forms a dibasic acid attacked only with dif- IO ficnlty by nitric acid, which is soluble only with difficulty in water and alcohol, from the Witnesses ARTHUR Gi'IHUN,

latter of which it crystallizes in small needles JACOB ADRIAN. 

